Up to now, Patent Literature 1 discloses an ejector that is applied to a vapor-compression refrigeration cycle device. In the ejector disclosed in Patent Literature 1, a refrigerant that flows out of an evaporator through a refrigerant suction port provided in a body is drawn by a suction action of supersonic jet refrigerant jetted from a nozzle passage for reducing the pressure of the refrigerant. Then, in a diffuser passage, a mixture refrigerant of the jet refrigerant and a suction refrigerant (that is, the refrigerant on an evaporator outlet side) is raised in pressure and flow out to an intake side of a compressor.
In more detail, in the ejector disclosed in Patent Literature 1, a passage formation member, which is a substantially conical valve body portion, is disposed inside the body, and a refrigerant passage having an annular cross section is provided between an inner surface of the body and a conical lateral surface of the passage formation member. A portion of the refrigerant passage on a most upstream side in a refrigerant flow is used as a nozzle passage, and a portion of the refrigerant passage on a downstream side of the nozzle passage in the refrigerant passage is used as a diffuser passage.
Further, in Patent Literature 1, a swirling space is provided in the body of the ejector to swirl the refrigerant flowing into the nozzle passage around a center axis of the passage formation member. In the swirling space, a liquid-phase refrigerant flowing out of a radiator is swirled so that the refrigerant on a swirling center side is reduced in pressure and boiled. Then, the refrigerant in a two-phase separation state in which a columnar gas-phase refrigerant (hereinafter referred to as “gas column”) is generated on a swirling center side flows into the nozzle passage.
With the above configuration, in the ejector disclosed in Patent Literature 1, the boiling of the refrigerant in the nozzle passage is promoted and an energy conversion efficiency when converting a pressure energy of the refrigerant into a kinetic energy in the nozzle passage is to be improved. In addition, the energy conversion efficiency of the ejector as a whole (hereinafter referred to as “ejector efficiency”) is to be improved.
Further, the ejector disclosed in Patent Literature 1 includes a drive mechanism that displaces the passage formation member to change a passage cross-sectional area of the refrigerant passage. As a result, in the ejector disclosed in Patent Literature 1, the ejector is intended to be operated appropriately with a change in the passage cross-sectional area of the refrigerant passage according to a load variation of the applied refrigeration cycle device.